Composition of materials for dentists&#39; or other uses.



UNITED STATES CROSS REFERENCE PATENT OFFICE. I

STEiVART J. SPENGE, OF I-IARRIMAN, TENNESSEE.

SPECIFICATION forming part of Letters Patent No. 716,491, dated December 23, 1902. Application filed September 5. 1902- Serlal No. 122,214- (No specime'na) To all whom it may concern: 7

Be it known that I, STEWART J SPENCE, a citizen of the United States, residing at IIarriman, in the county of Roane and State of Tennessee, have invented a new and useful Composition of Materials for Dentists or other Uses where aHard and Non-Expansive Plaster is Desired for Making Molds and Taking Impressions, of which composition the following is a specification.

My composition consists of the following ingredients combined in proportions stated, viz: plaster-of-paris, ten and th roe-fourth s ounces; Portland cement, three and three-fourths ounces; sand, one and one-half ounces; pulverized sulfate of alumina and potash, (being the oflicinal alum,) seventy grains; pulverized citric acid, six grains. These ingredients are to be thoroughly mixed while in the powder, then add water and stir one minute. I

In using the above-named composition sufficient water should be applied to reduce the powder to a mortar consistency,

When used as above directed, this composition will harden in ten minutes.

By the use of the above materials the ex pansion of plaster-of-paris during the process of making artificial dental plates is entirely prevented, thereby producing better fitting dental plates.

This composition also possesses a quality of hardness over similar com positions or plasterof-paris which renders it less liable to fracturefrom any cause or crush out of shape during the operation of compression, or forcing the plaster mold or form into the vulcanizable rubber, thereby securing a much more perfect fit of dental plates.

\Vhat I claim, and desire to secure byLetters Patent of the United States, is

1. The herein-described composition of materials consisting of plaster-of-paris, Portland cement, sand, pulverized sulfate of alumina and potash, pulverized citric acid, and water, substantially as described, and for the purposes specified.

2. The herein-described composition of materials for making plaster casts or molds consist-ing of ,p'laster-of-paris, ten and threefourths ounces; Portland cement, three and three-fourths ounces; sand, one and one-half ounces; pulverized sulfate of alumina and potash, (being the oilicinal alum,) seventy grains; pulverized citric acid, six grains, substantially as described.

STE\VART J. SPENCE.

' Witnesses: V

NELLIE BLANQHE IIARSH, G. H. DUTHIE.

EXAMINE, 

